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Walking Pneumonia in Children

Pneumonia is a serious lung infection that can be life threatening for some people. But a milder type of pneumonia is called "walking pneumonia." It is often caused by the germ Mycoplasma pneumoniae. Adults and children with this illness may feel unusually tired and run down. But they may not know they have pneumonia and go on about their business.

Teen girl at doctor's office

Facts about M. pneumoniae

  • About 2 million of these infections occur each year in the U.S.

  • The M. pneumoniae bacteria can also cause bronchitis and a number of upper respiratory tract infections.

  • M. pneumoniae is quite contagious. It can spread between people through bodily fluids, including phlegm that is coughed up. It can also spread through airborne droplets from sneezing, coughing, or talking. It is most easily spread among people who are in close contact with one another. This includes those living within households, military barracks, camps, and college dorms. M. pneumoniae infections can spread through whole communities as well.

  • M. pneumoniae is very common in school-aged children. It's the most common cause of pneumonia in this age group. But these infections are rare in children younger than 5 years old.

  • M. pneumoniae infections can occur at any time of year, but they are most common in the fall and winter.


M. pneumoniae infections can cause a number of symptoms:

  • Fever. The fever can be high, but it is usually low grade.

  • Fatigue

  • Headache

  • Skin rash

  • General feeling of sickness

  • Cough. This usually progresses from a dry cough to a productive cough.

  • Ear infections

  • Croup

  • Sinus infection

  • Sore throat

Children who have reactive airway disease may have wheezing as a result of the infection.

Symptoms may appear anywhere from 2 to 3 weeks after exposure to the bacteria and may last from a week to a month.

Diagnosis and treatment

Doctors can usually diagnose the infection based on the child's symptoms and a chest X-ray. Special diagnostic tests can diagnose the bacteria. But these usually aren't needed, and not all areas of the U.S. have these tests. Blood tests can find antibodies to the bacteria, but these usually aren't needed.

Often, mild respiratory infections such as upper respiratory infections and bronchitis clear up on their own and don't need treatment with medicine. But when symptoms are more severe and pneumonia or ear infections develop, your child's healthcare provider may prescribe antibiotics.


No vaccine is available to prevent a M. pneumoniae infection. Practicing good hygiene can help. This includes teaching kids to cover their nose and mouth when they cough or sneeze and to wash their hands often. These measures can help prevent other infections, too.

What else you need to know

M. pneumoniae infections are rarely serious. They respond well to antibiotics. And they typically clear up even without treatment. Deaths are most common in older adults or in people with other health conditions, including sickle cell disease.

People who have already had a M. pneumoniae infection do develop some immunity. But this usually doesn't last for a lifetime. A second infection from the bacteria is possible, but the illness is likely to be a milder version. 

Online Medical Reviewer: Adler, Liora C, MD
Online Medical Reviewer: Bass, Pat F III, MD, MPH
Date Last Reviewed: 11/1/2016
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